5 Surprising Reasons Why Poor Sleep Is Wrecking Havoc On Your Health, Hormones + Managing Weight

Written and medically reviewed by Dr. Courtney Ranieri, ND, a licensed naturopathic doctor registered with the College of Naturopaths of Ontario (Reg. #3726). Last reviewed July 2026.

If you've ever gone to bed too late or had a few nights of disjointed sleep, you know that a lack of sleep makes you more irritable, crave carbs and feel generally blah. The more we learn about sleep, the more we understand its importance for overall health, hormones and weight.

One key question I ask every patient is: do you have refreshing sleep? If you don't wake up feeling refreshed, we need to work on improving your sleep.

1. Poor sleep could be causing you to lose less weight

Short sleep duration is one of the strongest risk factors for obesity and a higher BMI. One study found that getting only 6.5 hours per night increases cortisol, appetite and weight gain. Another looked at two groups eating the exact same calories and found that those who were sleep-deprived lost 55% less weight than those who slept well.

2. Poor sleep affects your hormones and food cravings

• Lack of sleep raises ghrelin, our appetite-stimulating hormone, increasing cravings and calorie intake.
• It decreases leptin, our satiety hormone responsible for feeling full.
• It raises cortisol (your stress hormone), which leads to low energy, weight gain and cravings for carbs and sugar.

3. Poor sleep can impact thyroid health

Thyroid hormones regulate metabolic rate, energy, heart rhythm, menstrual cycles, mood and digestion. One study noted TSH levels were reduced by more than 30% a few days after sleep deprivation. Low thyroid function is associated with weight gain, slower cognition, low energy, low mood, hair loss and dry skin.

4. Poor sleep makes you dehydrated

One study of 25,000 adults showed that people who slept 6 hours per night had a 59% higher chance of being dehydrated than those who slept 8 hours.

5. Poor sleep can increase cardiovascular risk

Those who don't get enough sleep are at greater risk of heart disease or stroke than those who sleep 7 to 8 hours per night. Many studies also connect short sleep duration with Type 2 Diabetes due to increased insulin release.

5 ways to optimize your sleep

1. Avoid screens 30 minutes before bed. Blue light suppresses melatonin, prolongs time to fall asleep and reduces sleep quality. Try blue-light blocking apps or glasses.
2. Make bed-time a ritual. Ease into sleep with relaxing activities like reading, journalling or meditation, and keep your room at a comfortable, cool temperature.
3. Supplements can help. Melatonin, GABA, L-Theanine and magnesium have all been shown to help. We can also test your melatonin levels using DUTCH Comprehensive Hormone Testing.
4. Avoid coffee, alcohol and stimulants in the afternoon and evening. Caffeine can stay elevated for 6 to 8 hours, and alcohol alters nighttime melatonin production.
5. Get some sunshine during the day. A study found that 2 hours of daytime bright light increased sleep by two hours and sleep efficiency by 80%.

Always check in with your Naturopathic Doctor or other health care provider before starting any treatments or making changes to your healthcare plan.

About the author

Dr. Courtney Ranieri, ND is a board-licensed naturopathic doctor and the founder of Somewhere Health. She earned her Doctor of Naturopathic Medicine at the Canadian College of Naturopathic Medicine in Toronto and holds an Honours Bachelor of Science from the University of Western Ontario. Her clinical focus spans hormonal health, fertility, digestion, and women's health, with advanced training in pelvic floor therapy and integrative fertility care.

Book a visit with Dr. Courtney